I purchased a FBV Express MKII for my Spider IV 15 so I wouldn't have to go to my amp to change channels. I figured it would be as simple as just using the provided CAT-5 cable to connect the Pedal to the amp. When this didn't work I went through the process of calibrating it at least ten times. The calibration process worked. It went from 1 to 4 and all seven lights lit up. I unplugged it from the amp and reconnected it only to have it do nothing. I spent about an hour trying to find a USB cable to connect it to the computer to use the Line 6 Monkey to update it only to have it be fully updated. I preformed a factory reset just to be safe. I re-calibrated it to the amp and still nothing. So I then used the Line 6 FBV Control to program the pedal only to still have it not function with the amp. Does anybody know how to fix this?

This sounds like it may be an issue with your amp, but the first thing to do is check the CAT-5 connector jacks for bent pins and then try a different CAT-5 cable. Note that the connectors for that cable - both to the pedal and the amp - are not very robust and bent connector pins are not unusual.

This sounds like it may be an issue with your amp, but the first thing to do is check the CAT-5 connector jacks for bent pins and then try a different CAT-5 cable. Note that the connectors for that cable - both to the pedal and the amp - are not very robust and bent connector pins are not unusual.

After posting this I did try a different CAT 5 cable but it didn't seem to make any difference. So the issue is most likely in the amp and not in the FBV Express?